Introduction

Botulinum neurotoxin (BoNT) has been used effectively to alleviate pain in many pain disorders and has been proven to be a good choice for treatment of neuropathic pain. There have been no major side effects, only minor local infection. Randomized controlled studies and open-label studies indicate BoNT is beneficial in diabetic neuropathic pain, trigeminal neuralgia and postherpetic neuralgia (Piovesan et al., 2005; Ranoux et al., 2008; Yuan et al., 2009; Xiao et al., 2010). This chapter discusses the putative mechanisms of BoNT action and injection methodology for these three conditions.

Peripheral and central sensitization processes are involved in the pathophysiology of neuropathic pain (Baron, 2006; Pace et al., 2006). Abnormal muscle contraction, released substance P and calcitonin gene-related peptide also play significant roles in hyperalgesia of neuropathic pain. An ideal therapy for neuropathic pain should block these pain-inducing pathways as completely as possible. Muscle paralytic mechanisms, vasodilatation, pain-related neurotransmitter blockage, peripheral inflammatory pain inhibition and the inhibition of central pain perception contribute to the effectiveness of BoNT for neuropathic pain (Ranoux et al., 2008; Yuan et al., 2009; Neumeister et al., 2009).